// 云函数入口文件
const cloud = require('wx-server-sdk')
cloud.init({
  env: cloud.DYNAMIC_CURRENT_ENV
})

// 生成随机字符串
exports.main = async (event, context) => {
  let randomFlag = event.randomFlag;
  let min = event.min;
  let max = event.max;
  var str = '',
    range = min,
    arr = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
      'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l',
      'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
      'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
      'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'
    ];
  //随机位数
  if (randomFlag) {
    range = Math.round(Math.random() * (max - min)) + min;
  }
  //每位随机字符 
  for (let i = 0; i < range; i++) {
    let pos = Math.round(Math.random() * (arr.length - 1));
    str += arr[pos];
  }
  return str;
}